The present invention relates to tooth spacers and to a method of making a tooth spacer for use in shaping tooth filling material, such as composite resin, which has been placed in a tooth cavity preparation and for other dental applications.
In dentistry, teeth which are subject to decay are typically drilled or otherwise prepared by removing the decayed tooth material and creating a form for receiving filling material. This leaves an aperture, slot or other void in the tooth which needs to be filled with composite resin or other filling material. When dentists fill class 2 cavity preparations, they typically insert a temporary substrate adjacent to the cavity preparation to contain and control the flow of filling material. The temporary substrate that dentists have traditionally used is an elongated band called a matrix band. The bands are typically placed in some type of a retaining device and then tightened around the prepared tooth by rotating a portion of the retaining device with the tightening being accomplished shortly before the filling process is begun. One example of a matrix band is found in U.S. Pat. No. 5,380,198 to Suhonen. This particular band has at least one window covered by a transparent strip of plastic such as cellulose acetate. The plastic strip rests against the dental filling material which may be cured using light. This patent also mentions retaining the matrix band in position with the aid of a matrix tightener such as used in a Tofflemire system.
Since most of the composite resins used to fill teeth today are light cured resins, clear plastic bands offer significant advantages over metal matrix bands. Composite resin can be observed by a dentist through the clear plastic band to ensure that there are no unfilled voids before curing. In addition, the composite resin may then be cured by shining light through the clear plastic band to ensure a better depth of cure. However, clear plastic matrix bands which are known to the inventor have been composed of strips of mylar (polyester) which is at least 0.0015 inch thick or plastic materials such as mentioned in U.S. Pat. No. 5,380,198. The materials in U.S. Pat. No. 5,380,198 are also understood to be relatively thick. This patent equates in one example, the thickness of the plastic to the thickness of a steel band included in the device of e.g., 0.05 mm thickness.
Therefore, there is a need for an improved method for producing tooth spacers for applications such as shaping tooth filling material and for improved tooth spacers. The present invention does not require the solution of all of the problems of the prior art. Instead, the invention is directed toward new and unobvious features and methods set forth in this disclosure both alone and in combination with one another and as set forth in the claims below.
In accordance with one embodiment, a method of making at least one tooth spacer is disclosed, the tooth spacer being designed for insertion between the interproximal surfaces of at least one pair of adjacent teeth during a dental procedure, the adjacent teeth having a proximate area where the teeth are closest to or in contact with one another. In accordance with the method of this embodiment, first and second tooth spacer body portions are provided which each have at least one opening therethrough. A film is positioned at least partially between the first and second tooth spacer body portions. The respective openings through the tooth spacer body portions are at least partially aligned with one another and the film is visible through at least the aligned portions of the at least partially aligned openings. The film and first and second tooth spacer body portions are interconnected such that only the thickness of the film is present at least at one proximate tooth contact location of the tooth spacer. The at least one proximate tooth contact location is positioned where the openings are at least partially aligned and the film is present. As a result, the at least one proximate tooth contact location of the tooth spacer may be positioned at the proximate area between the adjacent teeth. In this case, only the thickness of the film is present in the proximate area between the adjacent teeth. The tooth spacer with the film is usable in shaping filling material especially in the proximal part of the tooth being filled.
The film may be a thin polymer sheet material. Preferably, the thickness of the sheet material film positioned between the proximal or adjacent most surfaces of the two adjacent teeth during filling of one of the teeth is no more than 0.0005 inch and desirably from about 0.0003 inch to 0.0006 inch. A light transmissive material or optically transparent material such as clear polyethylene may be used. The two body portions hold the film in place to span at least the aligned portions of the at least partially aligned openings. The assembled tooth spacer is flexible enough in one form so that it can be easily bent or wrapped at least partially around a tooth to be filled. The tooth spacer body portions may be elongated so that they may be wrapped entirely around a tooth with the tooth spacer being flexible enough to closely follow the natural unprepared contours of the tooth being filled. In some applications a conventional mechanism may be used to tighten the tooth spacer and to hold it in place during the dental procedure.
The tooth spacer body portions may be of the same or of a different thickness and may also have a total thickness which is no greater than 0.003 inch to 0.004 inch without the thickness of the film. As a specific example, if the tooth spacer body portions are of the same thickness, they may each, for example, have a thickness which is no greater than 0.002 inch, with 0.0015 inch being a more specific example. Each of the tooth spacer body portions may be formed from sheet material which may be of a homogenous single layer of material such as metal, with stainless steel being a specific example. The film may also be a single layer of film. Alternatively, and less desirably, the components of the tooth spacer body portions may be laminated of multiple layers.
In a more specifically desirable embodiment, the tooth spacer body portions may be of an identical size and shape and may be substantially aligned with one another with the openings through the respective body portions also being substantially aligned. By substantial alignment it is meant that the boundaries of the openings match one another within manufacturing tolerances as opposed to being deliberately offset.
In accordance with another aspect, each tooth spacer body portion may be elongated with at least first and second spaced apart openings. The first opening in the first tooth spacer body portion may be at least partially aligned with the first opening of the second tooth spacer body portion. In addition, the second opening of the first tooth spacer body portion may be at least partially aligned with the second opening of the second tooth spacer body portion. In addition, the film may entirely span the first and the second at least partially aligned openings. In this example, when the tooth spacer is wrapped around a tooth, the respective first openings may be positioned in the proximate area between the tooth and a first adjacent tooth and the respective second openings may be positioned in the proximate area between the tooth and a second adjacent tooth with the second adjacent tooth, being on the opposite side of the tooth from the first adjacent tooth.
Interconnection of the first and second tooth spacer body portions with the film may be accomplished in a number of ways such as adhesively or otherwise. Desirably this interconnection is accomplished at least in part by compressing and heating the film to heat fuse or heat seal the film and first and second tooth spacer body portions together. The film may be heated and simultaneously compressed at plural discrete spaced apart locations. Elongated heating elements may be utilized to apply both heat and pressure to one or both of the tooth spacer body portions to accomplish this heat fusion. The portion of the film exposed at the openings may be shielded from heat to prevent distortion of the film.
As a further aspect, the tooth spacer has a gingival edge portion which is to be positioned next to the gingiva of a patient during a dental procedure. At least one of the first and second tooth spacer body portions, and in one approach each of the first and second tooth spacer body portions, have a gingival edge portion with a section of reduced thickness to facilitate insertion of the interconnected tooth spacer between the adjacent teeth.
As another aspect, the openings through which the film is exposed when the tooth spacer is assembled may be spaced inwardly from the perimeter edge of the tooth spacer body portions and of the assembled tooth spacer such that the film in the openings is entirely surrounded by a portion of the respective tooth spacer body portions.
First and second elongated tooth spacer body portions may be provided which, when interconnected into a tooth spacer, have first and second side portions disposed on opposite sides of a central portion. In one form, only one of the respective first and second side portions may have at least partially aligned openings in the first and second elongated tooth spacer body portions through which the film is visible. The tooth spacer has a gingival edge and this embodiment may include reducing the thickness of a portion of the gingival edge along the one of the first and second side portions which does not have the at least partially aligned openings.
In a specific approach, the tooth spacer may be formed from a stack comprised of a first sheet which defines a plurality of first tooth spacer body portions and a second sheet which defines a plurality of second tooth spacer body portions. The stack also includes a sheet of film positioned between these first and second sheets. In this example, first tooth spacer body portions on the first sheet are aligned with second tooth spacer body portions on the second sheet. In addition, the first tooth spacer body portions and second tooth spacer body portions each include at least one opening with respective openings of first tooth spacer body portions being at least partially aligned with corresponding respective openings of the second tooth spacer body portions and with the film spanning and being visible through the at least partially aligned openings. The sheets and film are then interconnected, such as by heat fusing. The individually defined tooth spacer body portions may be connected to their respective sheets by severance portions which are then severed following the interconnection of the sheets and film to form the individual tooth spacers. Again, the tooth spacers may include two or more spaced apart openings. In addition, the respective sheets may be each provided with at least one alignment opening and more typically with at least two such alignment openings to facilitate the alignment of the sheets and film which are to be assembled into the tooth spacers.
In the event heat fusion is used to assemble the tooth spacers, typically heat is applied at locations spaced from the openings so as to not adversely affect film exposed in the openings. In addition, the film may be heat fused at discrete locations spaced about the entire periphery of the aligned openings.